Physconia
Physconia Poelt, 1965
| Common name | Frost Lichens | |
|---|---|---|
| Field Characters | Small, narrow-lobed, foliose chlorolichens. Thalli typically attached throughout or slightly ascending at the lobe tips, varying from disparate lobes to forming large orbicular thalli and extensive colonies. Lobes typically < 2 mm across, branching regularly, equal in width throughout. Upper cortex grey to brown, often extensively pruinose (giving the genus the common name of Frost Lichens). Medulla white, in some species yellow. Soralia common, varying from marginal to terminal and labriform, and in some species, developing isidia and lobules. Lower cortex typically black, in some species pale. Rhizines typically abundant, black, squarrosely branched and often visible as a fringe of pipecleaner like structures around the lobe edge. Apothecia rare in most species, with a dark disk ofen obscured by pruina and thalline margin concolorous with the upper cortex. | |
| Similar species & genera |
Phaeophyscia: generally lacking regular pruina, rhizines simples to sparsely squarrosely branched. | |
| Ecology | Variable; most species are epiphytic or on downed wood, some are terricolous, and a few saxicolous. Some species are restricted to grassland and alpine habitats, others are rare in the mountains, and a handful of species common across the forested regions. | |
| Chemistry | Upper cortex all spot tests negative (no substances detected). Medulla variable, from all spot tests negative to K+ yellow in species with secalonic acid. | |
| Molecular support |
In progress, as part of work by Esslinger and Leavitt to better delineate Physciaceae in North America. | |
| Links |
Species recorded in Alberta: 7
- P. detersa (Nyl.) Poelt Syn.: Physcia detersa ACIMS, ABMI
- P. enteroxantha (Nyl.) Poelt ACIMS
- P. grumosa Kashiw. & Poelt (Esslinger & Dillman 2010) Confirmed by Ted Esslinger, not yet in ACIMS
- P. isidiigera (Zahlbr.) Essl. ACIMS
- P. labrata Esslinger, McCune & Haughland AB (Type from near Hinton)
- P. muscigena (Ach.) Poelt Syn.: Physcia muscigena ACIMS, ABMI
- P. perisidiosa (Erichsen) Moberg ACIMS, ABMI
Click here for a pdf key to the Physconia of Alberta v. 2025
RENR Students: Know Physconia muscigena– be able to key this species out or recognize it.
Resources
Brodo, I. M. 2016. Keys to the lichens of North America. Revised and Expanded. Yale University Press, in collaboration with the Canadian Museum of Nature.
Brodo, I. M., S. D. Sharnoff, and S. Sharnoff. 2001. Lichens of North America. Yale University Press, New Haven and London.
Goward, T., B. McCune, and D. Meidinger. 1994. The Lichens of British Columbia Illustrated Keys. Part 1 – Foliose and Squamulose Species. Ministry of Forests Research Program, Province of British Columbia.
